An X-wing aircraft uses a rigid rotor/wing utilizing circulation control airfoils. The rotor is driven mechanically and the rotor blades operate essentially in fixed pitch. Collective and cyclic lift control is basically achieved by control of air circulation about the blade airfoils. This is done by blowing compressed air through leading edge and trailing edge openings on the rotor blades, modulating the amount of air being ejected through the openings. A limited amount of collective pitch control, however, may be achieved through mechanical linkage.
The rotor system for an X-wing aircraft includes a hub and attached rotor blades and a pneumatic system for delivering compressed air separately to the leading edge and the trailing edge of the individual rotor blades at the desired pressure and mass flow. The pneumatic system includes an air storage chamber, or plenum, and it is the plenum and its relation to the mechanical pitch control system which is the subject of this invention.
A circulation control rotor system is described in the report titled "Circulation Control Rotor Flight Demonstrator" by David R. Barnes, Douglas G. Kirkpatrick and George A. McCoubrey presented at an American Helicopter Society Mideast Region Symposium in August, 1976. The report titled "Status Report on Advanced Development Program Utilizing Circulation Control Rotor Technology" by Kenneth R. Reader, Douglas G. Kirkpatrick and Robert M. Williams, Paper No. 44 presented at the Fourth European Rotorcraft and Powered Lift Aircraft Forum, Stresa, Italy, Sept. 13-15, 1978 describes an X-wing development program.
Davidson et al U.S. Pat. No. 3,139,936 and Flint et al U.S. Pat. Nos. 3,348,618 and 3,349,853 describe a control mechanism for a helicopter having circulation control with compressed air being supplied through the rotor pillar. Cheeseman et al U.S. Pat. No. 3,524,711 and Seed U.S. Pat. No. 3,567,332 describe helicopter rotors employing circulation control.